public async Task CreateOfferReport(CrudAPI api, GiftProject giftProject)
{
    var order = ConvertProjectToOrder(giftProject);

    var invoiceParams = new InvoiceParameters()
    {
        Date = DateTime.Now,
        InvoiceNumber = order.Name,
        order = order,
        lines = order.OfferLines,
        ReturnPDF = true,
        SendByOutlook = false,
        SendXML = false,
        DocumentType = CompanyLayoutType.Offer,
        ShowInvoice = false,
        Simulate = false
    };
    var invoice = await invoiceParams.PostInvoice(new InvoiceAPI(api));
    var data = invoice.pdf;

    var fileName = "Offerte 123";
    var attachment = new UserDocsClient()
    {
        _Data = data,
        _Text = fileName,
        _DocumentType = FileextensionsTypes.PDF
    };
    return attachment;
}